Telelever damping

[Corvus]

There's a thread opened up recently regarding the funny plastic bottles in the fork leg.

Got me thinking.

If the Telelever forks need oil anyway, then why isn't the damping function carried out there? Leaving just a coil spring and nothing else where there is now a front shock. What's the reason?

Doesn't even have to be a coil spring. Could maybe be a torsion spring even? Rubber perhaps? Bit o chewing gum....

Just a thought!

[RiceBurner]

There's a thread opened up recently regarding the funny plastic bottles in the fork leg.

Got me thinking.

If the Telelever forks need oil anyway, then why isn't the damping function carried out there? Leaving just a coil spring and nothing else where there is now a front shock. What's the reason?

Doesn't even have to be a coil spring. Could maybe be a torsion spring even? Rubber perhaps? Bit o chewing gum....

Just a thought!

The forks aren't doing any suspension work whatsoever - they're just holding the front wheel straight. All the suspension work is done by the swinging arm and it's associated coil-shock.

Therefore it makes sense to use a standard damping+coil unit that can be bought virtually 'off-the-shelf' from the suspension manufacturer. Then fork tubes then just need some lubrication oil and are far cheaper to make.

[Corvus]

...............The forks aren't doing any suspension work whatsoever - they're just holding the front wheel straight. All the suspension work is done by the swinging arm and it's associated coil-shock.

Therefore it makes sense to use a standard damping+coil unit that can be bought virtually 'off-the-shelf' from the suspension manufacturer. Then fork tubes then just need some lubrication oil and are far cheaper to make.

Hi.

Yes, I realised that the forks don't perform suspension duties, just steering. I just wondered if they could be made to perform damping duties, given that there is oil in there in the first place. I'm sure it would work, although it can't be the best solution otherwise bmw would have done it I guess!

I may be wrong here, but I think the very first incarnation of the Saxon design had the forks as dampers? Springs as well I think. I'll check that. Back tracking in time, the main objective of the day was anti dive and stiffer front end. Later versions definitely had a separate full shock and the very last version looks exactly like the Telelever as we know it. So there is probably a good technical reason why even the damping forces are best kept upstream of the steering. Certainly the front "frame" would need to be a little stronger if damping forces were transmitted into it.

Maybe economic reasons play a part, as your second paragraph. Although damped forks are not that difficult. And there's nowt cheaper than a simple coil spring. Wouldn't even need a strut. Be like a car wishbone.

Maybe, also, it's easier to adopt ESA and the like with a dedicated suspension shock absorber.

Interesting thoughts though.

Cheers.

[Corvus]

Some good pictures on here.

The top one is all about anti dive. You can see how the train of thought might develop. The next two are later wishbone versions, I think. I'll see if I can find a picture of an early incarnation.

http://www.pinkfishmedia.net/forum/show ... 837&page=2

[Corvus]

...............
I may be wrong here, but I think the very first incarnation of the Saxon design had the forks as dampers? Springs as well I think. I'll check that.......

Nah. Can't find any evidence of that. Must have imagined it. I'm wrong.

Besides, thinking it through, it doesn't stack up engineering wise very well. Doesn't make any real structural use of the A frame, to say the least.

[Corvus]

The taylormade moto2 bike certainly has the spring function in the forks. Not sure about damping.

So the A arm to this designer is more about supporting the forks under braking to eliminate stiction, more than anything else. Although some control over dive is also there too, and adjustable no doubt.

Interestingly gaetano cocco says that the forces placed upon the forks due to weight transfer when braking, go a long way to negating the forces imposed by braking reaction itself, because they act broadly opposite each other. Makes sense to me GC.

Mmm. Fiendish things these motorcycles.

[Tapio]

There's also the question of where components are placed regarding weight. You want to keep unsprung weight as low as possible. Taking the spring/damping action out of the forks reduces unsprung weight. I think.
I've given this some thought, but haven't come to an answer: is the Telelever A-arm, and the swingarm unsprung or sprung weight?
If A-arm is sprung, then it's a good idea to move spring/dampening there, but if it isn't, then it doesn't matter.

[Corvus]

There's also the question of where components are placed regarding weight. You want to keep unsprung weight as low as possible. Taking the spring/damping action out of the forks reduces unsprung weight. I think.
I've given this some thought, but haven't come to an answer: is the Telelever A-arm, and the swingarm unsprung or sprung weight?
If A-arm is sprung, then it's a good idea to move spring/dampening there, but if it isn't, then it doesn't matter.

Hi tapio.

It definitely counts as unsprung weight. It's just more difficult to work out that's all. The parts which go up and down or move in any direction, which are moving with respect to suspension movement, all count in the calculation. Even the calculation for the forks on a (bmw) Telelever setup are tricky to calculate, in my view, because they follow a peculiar path.

Keeping the springs out of the forks and onto the A arm does reduce steered inertia though. Shame we can't get rid of that pesky oil as well! Which, of course, is what the plastic bottles were about, as far as I can tell.

I wonder if the Taylor bike has gas springs?

With regard to moving the spring and/or damping function into the forks, surely it's not just unsprung weight which is the consideration, but the whole way the loads are resolved into the frame. Look at the later versions of the front frame. It is a masterpiece of design. It's so flimsy looking, but very strong in the direction it needs to be. That situation would change somewhat if the suspension loads went fully up into it. I think! As you say, it's a little tricky to come to terms with.